The Thermacell Proflex Heated Insoles Replacement Battery Pack in Grey is a set of two portable and lightweight foot warmers perfect for winter sports activities like skiing, snowboarding, and snowshoeing. With a battery life of up to 500 charges and each charge lasting up to 5 hours, these reusable insoles provide long-lasting warmth. The water-resistant design ensures they stay powered up in any weather conditions, making them a reliable and convenient accessory for staying comfortable during outdoor winter adventures. Made by ThermaCell, a trusted brand in foot warming technology, these insoles are a must-have for cold weather sports enthusiasts.